1. Field of the Invention
This invention relates to an adaptive strategy for adjusting engine control variables.
2. Prior Art
Conventional engine control strategy includes the use of engine torque and engine RPM to select values of spark angle and exhaust gas recirculation (EGR) fraction. For example, in a computer controlled engine, such as that disclosed in U.S. Pat. No. 3,969,614 issued to Moyer et al and assigned to the assignee hereof, the disclosure of which is hereby incorporated by reference, the computer controls the engine by selecting values from tables for spark angle and exhaust gas recirculation based on measurements of instantaneous engine revolutions per minute (RPM) and manifold absolute pressure (MAP).
In making the compromises among feedgas emissions levels, mileage, and catalyst size, as indicated by the system inputs of engine RPM and manifold fold pressure, it is not generally possible to operate the engine at its most efficient calibration. This results in a loss of fuel mileage from the ideal. It would be desirable to develop additional characterizations of the engine which could be used to improve the selection of engine control of variables. These are some of the problems this invention overcomes.